Barry Sanders | University of Calgary (original) (raw)
Dr Barry Sanders is AITF iCORE Strategic Chair in Quantum Information Science and Director of the Institute for Quantum Science and Technology at the University of Calgary. Dr Sanders also holds a QianRen B Chair in the Division of Quantum Physics and Quantum Information of the National Laboratory for Physical Sciences at the Microscale at the University of Science and Technology China.
Dr Sanders received his Bachelor of Science degree from the University of Calgary in 1984 and a Diploma of Imperial College supervised by Professor Sir Thomas W. B. Kibble. He completed a PhD in 1987 at Imperial College supervised by Professor Sir Peter Knight. His postdoctoral research was supervised by Professor Gerard Milburn at the Australian National University then at the University of Queensland and by Professor Crispin Gardiner at the University of Waikato. Dr. Sanders joined the Physics Department of Macquarie University in 1991 and was there for 12 years, including 6 years as Department Head, before moving to Calgary in 2003.
Dr Sanders is especially well known for seminal contributions to theories of quantum-limited measurement, highly nonclassical light, practical quantum cryptography and optical implementations of quantum information tasks. His current research interests include quantum resources & algorithms, optical & atomic implementations of quantum information tasks and protocols, quantum processes in biological systems, and machine learning for quantum control.
Dr. Sanders is a Fellow of the Institute of Physics (U.K.), the Optical Society of America, the Australian Institute of Physics, the American Physical Society, and the Canadian Institute for Advanced Research. He is a past President of the Australian Optical Society past Founding Co-Chair of the Canadian Association of Physicists Division of Atomic, Molecular and Optical Physics and former Leader of the Optical Society of America Quantum Optical Science and Technology Technical Group.
Dr Sanders is Editor-in-Chief of New Journal of Physics, a former Associate Editor of Physical Review A, a former Editor of Optics Communications and a former editor of Mathematical Structures of Computer Science.
Supervisors: Peter L. Knight and T. W. B. Kibble
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Papers by Barry Sanders
We investigate a method for generating nonlinear phase shifts on superpositions of photon number ... more We investigate a method for generating nonlinear phase shifts on superpositions of photon number states. The light is stored in a Bose-Einstein condensate via electromagnetically induced transparency memory techniques. The atomic collisions are exploited to generate a nonlinear phase shift of the stored state. The stored light is then revived with the nonlinear phase shift imprinted upon it. We show that this method can be used as a nonlinear-sign gate in the regime where the Thomas-Fermi and mean-field approximations are valid. We test these approximations using realistic parameters and find that these approximations pass the standard tests for validity in a single-component condensate. However, for the two-component condensates considered here, we find that these conditions are insufficiently strict. We find a stronger set of conditions and show for the same set of parameters that the approximations are invalid.
Physical Review A, 1992
Erratum: Entangled coherent states [Phys. Rev. A 45, 6811 (1992)]. Barry C. Sanders. URL: http://... more Erratum: Entangled coherent states [Phys. Rev. A 45, 6811 (1992)]. Barry C. Sanders. URL: http://link.aps.org/doi/10.1103/PhysRevA.46.2966 DOI: 10.1103/PhysRevA. 46.2966 PACS: 42.50.Wm, 42.50.Dv, 03.65.Bz, 99.10.+g. ...
Proceedings of the National Academy of Sciences, 2010
Journal of the American Chemical Society, 2011
Transition-state theory (TST) is a widely accepted paradigm for rationalizing the kinetics of che... more Transition-state theory (TST) is a widely accepted paradigm for rationalizing the kinetics of chemical reactions involving one potential energy surface (PES). Multiple PES reaction rate constants can also be estimated within semiclassical approaches provided the hopping probability between the quantum states is taken into account when determining the transmission coefficient. In the Marcus theory of electron transfer, this hopping probability was historically calculated with models such as Landau-Zener theory. Although the hopping probability is intimately related to the question of the transition from the fully quantum to the semiclassical description, this issue is not adequately handled in physicochemical models commonly in use. In particular, quantum nuclear effects such as decoherence or dephasing are not present in the rate constant expressions. Retaining the convenient semiclassical picture, we include these effects through the introduction of a phenomenological quantum decoherence function. A simple modification to the usual TST rate constant expression is proposed: in addition to the electronic coupling, a characteristic decoherence time τ(dec) now also appears as a key parameter of the rate constant. This new parameter captures the idea that molecular systems, although intrinsically obeying quantum mechanical laws, behave semiclassically after a finite but nonzero amount of time (τ(dec)). This new degree of freedom allows a fresh look at the underlying physics of chemical reactions involving more than one quantum state. The ability of the proposed formula to describe the main physical lines of the phenomenon is confirmed by comparison with results obtained from density functional theory molecular dynamics simulations for a triplet to singlet transition within a copper dioxygen adduct relevant to the question of dioxygen activation by copper monooxygenases.
Physical Chemistry Chemical Physics, 2012
Over recent decades, quantum effects such as coherent electronic energy transfers, electron and h... more Over recent decades, quantum effects such as coherent electronic energy transfers, electron and hydrogen tunneling have been uncovered in biological processes. In this Perspective, we highlight some of the main conceptual and methodological tools employed in the field to investigate electron tunneling in proteins, with a particular emphasis on the methodologies we are currently developing. In particular, we describe our recent contributions to the development of a mixed quantum-classical framework aimed at describing physical systems lying at the border between the quantum and semi-classical worlds. We present original results obtained by combining our approach with constrained Density Functional Theory calculations. Moving to coarser levels of description, we summarize our latest findings on electron transfer between two redox proteins, thereby showing the stabilization of inter-protein, water-mediated, electron-transfer pathways.
Electronics Letters, 2006
Abstract Experimental waveguides, bends and power dividers in the woodpile electromagnetic bandga... more Abstract Experimental waveguides, bends and power dividers in the woodpile electromagnetic bandgap (EBG) material at Ku-band are demonstrated. Prototypes are fabricated from alumina, and use an efficient waveguide transition to enable high quality ...
Physica E: Low-dimensional Systems and Nanostructures, 2001
Australian Journal of Physics, 2013
CLEO: 2013, 2013
ABSTRACT We develop a theory for multi-channel passive optical interferometery with one or zero p... more ABSTRACT We develop a theory for multi-channel passive optical interferometery with one or zero photon entering each input port, and we show that the output photon coincidences yield information about immanants of the interferometer transformation matrix.
The N00N state, which was introduced as a resource for quantum-enhanced metrology, is in fact a s... more The N00N state, which was introduced as a resource for quantum-enhanced metrology, is in fact a special case of a superposition of two SU(2) coherent states. We show here explicitly the derivation of the N00N state from the superposition state. This derivation makes clear the connection between these seemingly disparate states as well as shows how the N00N state can be generalized to a superposition of SU(2) coherent states.
Microwave and Optical Technology Letters, Aug 24, 2005
For Doppler-broadened media operating under double-double electromagnetically induced transparenc... more For Doppler-broadened media operating under double-double electromagnetically induced transparency (EIT) conditions, we devise a scheme to control and reduce the probe-field group velocity at the center of the second transparency window. We derive numerical and approximate analytical solutions for the width of EIT windows and for the group velocities of the probe field at the two distinct transparency windows, and we show that the group velocities of the probe field can be lowered by judiciously choosing the physical parameters of the system. Our modeling enables us to identify three signal-field strength regimes (with a signal-field strength always higher than the probe-field strength), quantified by the Rabi frequency, for slowing the probe field. These three regimes correspond to a weak signal field, with the probe-field group velocity and transparency window width both smaller for the second window compared to the first window, a medium-strength signal field, with a probe-field group velocity smaller in the second window than in the first window but with larger transparency-window width for the second window, and the strong signal field, with both group velocity and transparency window width larger for the second window. Our scheme exploits the fact that the second transparency window is sensitive to a temperature-controlled signal-field nonlinearity, whereas the first transparency window is insensitive to this nonlinearity.
Charge qubits are promising quantum logical elements for performing quantum computation or as int... more Charge qubits are promising quantum logical elements for performing quantum computation or as intermediate states to prepare and read other qubit realizations such as spin or flux. Instead of idealizing the charge qubits at the outset and using standard quantum circuit theory, we use the extended Hubbard model as a first-principles model of charge qubit dynamics and model idealized proposals for charge-qubit circuits using this second-quantized description with short- and medium-range interactions. In particular we study how one- and two-qubit gates would perform for realistic systems, and we apply our theory to teleportation of a single charge qubit in a three-qubit system. We also discuss how to incorporate phonon noise into the model.
J Phys a Math Theor, 2010
We introduce a class of bipartite entanglement measures based on Rényi-α entropy, namely Rényi-α ... more We introduce a class of bipartite entanglement measures based on Rényi-α entropy, namely Rényi-α entanglement with an analytic formula in two-qubit systems for α >= 1. We also show that multi-qubit entanglement has a monogamy inequality in terms of Rényi-α entanglement for all α >= 2.
IEEE Antennas and Propagation Society International Symposium. Digest. Held in conjunction with: USNC/CNC/URSI North American Radio Sci. Meeting (Cat. No.03CH37450), 2003
Abstract We demonstrate two antennas that use two different electromagnetic bandgap materials. Th... more Abstract We demonstrate two antennas that use two different electromagnetic bandgap materials. The first is a thin, high gain resonator antenna formed from a three-dimensional electromagnetic bandgap material and a metallic ground plane. The second structure is a ...
By generalizing a quantum walk to include measurement of the path taken by the quantum walker, we... more By generalizing a quantum walk to include measurement of the path taken by the quantum walker, we show that quantum walks interpolate between a fully coherent quantum dynamics and a classical random walk, depending on how strongly the walker's coin state is measured; i.e., the quantum walk exhibits the quintessentially quantum property of complementarity.
We investigate a method for generating nonlinear phase shifts on superpositions of photon number ... more We investigate a method for generating nonlinear phase shifts on superpositions of photon number states. The light is stored in a Bose-Einstein condensate via electromagnetically induced transparency memory techniques. The atomic collisions are exploited to generate a nonlinear phase shift of the stored state. The stored light is then revived with the nonlinear phase shift imprinted upon it. We show that this method can be used as a nonlinear-sign gate in the regime where the Thomas-Fermi and mean-field approximations are valid. We test these approximations using realistic parameters and find that these approximations pass the standard tests for validity in a single-component condensate. However, for the two-component condensates considered here, we find that these conditions are insufficiently strict. We find a stronger set of conditions and show for the same set of parameters that the approximations are invalid.
Physical Review A, 1992
Erratum: Entangled coherent states [Phys. Rev. A 45, 6811 (1992)]. Barry C. Sanders. URL: http://... more Erratum: Entangled coherent states [Phys. Rev. A 45, 6811 (1992)]. Barry C. Sanders. URL: http://link.aps.org/doi/10.1103/PhysRevA.46.2966 DOI: 10.1103/PhysRevA. 46.2966 PACS: 42.50.Wm, 42.50.Dv, 03.65.Bz, 99.10.+g. ...
Proceedings of the National Academy of Sciences, 2010
Journal of the American Chemical Society, 2011
Transition-state theory (TST) is a widely accepted paradigm for rationalizing the kinetics of che... more Transition-state theory (TST) is a widely accepted paradigm for rationalizing the kinetics of chemical reactions involving one potential energy surface (PES). Multiple PES reaction rate constants can also be estimated within semiclassical approaches provided the hopping probability between the quantum states is taken into account when determining the transmission coefficient. In the Marcus theory of electron transfer, this hopping probability was historically calculated with models such as Landau-Zener theory. Although the hopping probability is intimately related to the question of the transition from the fully quantum to the semiclassical description, this issue is not adequately handled in physicochemical models commonly in use. In particular, quantum nuclear effects such as decoherence or dephasing are not present in the rate constant expressions. Retaining the convenient semiclassical picture, we include these effects through the introduction of a phenomenological quantum decoherence function. A simple modification to the usual TST rate constant expression is proposed: in addition to the electronic coupling, a characteristic decoherence time τ(dec) now also appears as a key parameter of the rate constant. This new parameter captures the idea that molecular systems, although intrinsically obeying quantum mechanical laws, behave semiclassically after a finite but nonzero amount of time (τ(dec)). This new degree of freedom allows a fresh look at the underlying physics of chemical reactions involving more than one quantum state. The ability of the proposed formula to describe the main physical lines of the phenomenon is confirmed by comparison with results obtained from density functional theory molecular dynamics simulations for a triplet to singlet transition within a copper dioxygen adduct relevant to the question of dioxygen activation by copper monooxygenases.
Physical Chemistry Chemical Physics, 2012
Over recent decades, quantum effects such as coherent electronic energy transfers, electron and h... more Over recent decades, quantum effects such as coherent electronic energy transfers, electron and hydrogen tunneling have been uncovered in biological processes. In this Perspective, we highlight some of the main conceptual and methodological tools employed in the field to investigate electron tunneling in proteins, with a particular emphasis on the methodologies we are currently developing. In particular, we describe our recent contributions to the development of a mixed quantum-classical framework aimed at describing physical systems lying at the border between the quantum and semi-classical worlds. We present original results obtained by combining our approach with constrained Density Functional Theory calculations. Moving to coarser levels of description, we summarize our latest findings on electron transfer between two redox proteins, thereby showing the stabilization of inter-protein, water-mediated, electron-transfer pathways.
Electronics Letters, 2006
Abstract Experimental waveguides, bends and power dividers in the woodpile electromagnetic bandga... more Abstract Experimental waveguides, bends and power dividers in the woodpile electromagnetic bandgap (EBG) material at Ku-band are demonstrated. Prototypes are fabricated from alumina, and use an efficient waveguide transition to enable high quality ...
Physica E: Low-dimensional Systems and Nanostructures, 2001
Australian Journal of Physics, 2013
CLEO: 2013, 2013
ABSTRACT We develop a theory for multi-channel passive optical interferometery with one or zero p... more ABSTRACT We develop a theory for multi-channel passive optical interferometery with one or zero photon entering each input port, and we show that the output photon coincidences yield information about immanants of the interferometer transformation matrix.
The N00N state, which was introduced as a resource for quantum-enhanced metrology, is in fact a s... more The N00N state, which was introduced as a resource for quantum-enhanced metrology, is in fact a special case of a superposition of two SU(2) coherent states. We show here explicitly the derivation of the N00N state from the superposition state. This derivation makes clear the connection between these seemingly disparate states as well as shows how the N00N state can be generalized to a superposition of SU(2) coherent states.
Microwave and Optical Technology Letters, Aug 24, 2005
For Doppler-broadened media operating under double-double electromagnetically induced transparenc... more For Doppler-broadened media operating under double-double electromagnetically induced transparency (EIT) conditions, we devise a scheme to control and reduce the probe-field group velocity at the center of the second transparency window. We derive numerical and approximate analytical solutions for the width of EIT windows and for the group velocities of the probe field at the two distinct transparency windows, and we show that the group velocities of the probe field can be lowered by judiciously choosing the physical parameters of the system. Our modeling enables us to identify three signal-field strength regimes (with a signal-field strength always higher than the probe-field strength), quantified by the Rabi frequency, for slowing the probe field. These three regimes correspond to a weak signal field, with the probe-field group velocity and transparency window width both smaller for the second window compared to the first window, a medium-strength signal field, with a probe-field group velocity smaller in the second window than in the first window but with larger transparency-window width for the second window, and the strong signal field, with both group velocity and transparency window width larger for the second window. Our scheme exploits the fact that the second transparency window is sensitive to a temperature-controlled signal-field nonlinearity, whereas the first transparency window is insensitive to this nonlinearity.
Charge qubits are promising quantum logical elements for performing quantum computation or as int... more Charge qubits are promising quantum logical elements for performing quantum computation or as intermediate states to prepare and read other qubit realizations such as spin or flux. Instead of idealizing the charge qubits at the outset and using standard quantum circuit theory, we use the extended Hubbard model as a first-principles model of charge qubit dynamics and model idealized proposals for charge-qubit circuits using this second-quantized description with short- and medium-range interactions. In particular we study how one- and two-qubit gates would perform for realistic systems, and we apply our theory to teleportation of a single charge qubit in a three-qubit system. We also discuss how to incorporate phonon noise into the model.
J Phys a Math Theor, 2010
We introduce a class of bipartite entanglement measures based on Rényi-α entropy, namely Rényi-α ... more We introduce a class of bipartite entanglement measures based on Rényi-α entropy, namely Rényi-α entanglement with an analytic formula in two-qubit systems for α >= 1. We also show that multi-qubit entanglement has a monogamy inequality in terms of Rényi-α entanglement for all α >= 2.
IEEE Antennas and Propagation Society International Symposium. Digest. Held in conjunction with: USNC/CNC/URSI North American Radio Sci. Meeting (Cat. No.03CH37450), 2003
Abstract We demonstrate two antennas that use two different electromagnetic bandgap materials. Th... more Abstract We demonstrate two antennas that use two different electromagnetic bandgap materials. The first is a thin, high gain resonator antenna formed from a three-dimensional electromagnetic bandgap material and a metallic ground plane. The second structure is a ...
By generalizing a quantum walk to include measurement of the path taken by the quantum walker, we... more By generalizing a quantum walk to include measurement of the path taken by the quantum walker, we show that quantum walks interpolate between a fully coherent quantum dynamics and a classical random walk, depending on how strongly the walker's coin state is measured; i.e., the quantum walk exhibits the quintessentially quantum property of complementarity.